An object, at a certain temperature can emit radiation. This type of radiation
is known as thermal radiation. The color of the radiation is dependent on the
temperature and (according to Serway and Faughn) the properties of the object.
As the temperature increases, the object begins to emit light.

The thermal radiations comes from accelerated charged particles near the surface
of the object. The charged particles would emit radiation. This is the classical
theory of thermal radiation.

A black body is an ideal system that absorbs all of the incident radiation
on it. As the amount of energy it emits increases, so does the black body's temperature.
As the temperature is increasing, the acme of the distribution move towards short
wavelength. This obeys Wien's displacement law.

λmaxT = 0.2898 × 10-2mK

Where λmax is the wavelength
at which the curve peaks and T is the temperature at which the object would
emit radiation.